The invention is related to a magnetic field sensor comprising a Hall-effect element.
Such magnetic field sensors are suitable, for example, for use in magnetometers which are designed for the measurement of two or all three components of a magnetic field.
The use of Hall-effect elements as magnetic field sensors has been normal for a long time. Hall-effect elements which are manufactured in conventional IC technology have all the advantages of this technology in particular the high reproducibility of their magnetic and electrical characteristics at comparatively low cost. For the measurement of the magnetic field component which is vertical to the chip surface, so-called horizontal Hall-effect elements are used while so-called vertical Hall-effect elements are used for measurement of the magnetic field component which is parallel to the chip surface. Vertical Hall-effect elements are electrically short-circuited to the substrate. Therefore, it is not easily possible to use two vertical Hall-effect elements which are turned by 90.degree. and integrated into the same chip for simultaneous measurement of the two components B.sub.z and B.sub.y of the magnetic field B which are parallel to the chip surface. Several magnetic field sensors are known from scientific literature which are based on the structure of the vertical Hall-effect element and which enable the simultaneous measurement of the two components B.sub.x and B.sub.y. These Hall-effect elements have five current contacts and four Hall contacts. From the article "a A 2-D vertical Hall magnetic field sensor using active carrier confinement and micromachining techniques" from M. Paranjape, L. Landsberger and M. Kahrizi, paper 295--PA 12 of the Konferenz Transducers 95--Eurosensors IX it is known to reduce the sensitivity of the HallI-effect element to feedover in that the zones relevant for the Hall-effect are formed as three-dimensional surface structures by means of micromechanical processes. In addition, it is known from the articles "Multi-dimensional detection of magnetic fields using, CMOS integrated sensors" by M. Paranjape and Lj. Ristic, IEEE Transactions on Magnetics, Vol. 27, No. 6, 1991 and "A 3-D vertical Hall magnetic-field sensor in CMOS technology" by M. Paranjape and I. Filanovsky, Sensors and Actuators A, 34 (1992) that a magnetic field sensor can be constructed which also enables the measurement of the component B.sub.z of the magnetic field B which is vertical to the chip surface by separating each of the four Hall contacts into two Hall contacts so that a total of eight Hall contacts are present. The sensitivity of these magnetic field sensors with regard to the component B.sub.z is however considerably lower than the sensitivity with regard to the B.sub.x or B.sub.y component.
The object of the invention is to propose a magnetic field sensor which can be easily manufactured and which is suitable for measuring a t least two, preferably all three components of a magnetic field with high local resolution.